Added note on thread safety to TypeConverter and SimpleTypeConverter javadoc

Issue: SPR-8659

spring-beans/src/main/java/org/springframework/beans/SimpleTypeConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,9 @@ package org.springframework.beans;
  * algorithm (including delegation to {@link java.beans.PropertyEditor} and
  * {@link org.springframework.core.convert.ConversionService}) underneath.
  *
+ * <p><b>Note:</b> Due to its reliance on {@link java.beans.PropertyEditor PropertyEditors},
+ * SimpleTypeConverter is <em>not</em> thread-safe. Use a separate instance for each thread.
+ *
  * @author Juergen Hoeller
  * @since 2.0
  * @see BeanWrapperImpl

spring-beans/src/main/java/org/springframework/beans/TypeConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,10 @@ import org.springframework.core.MethodParameter;
  * Interface that defines type conversion methods. Typically (but not necessarily)
  * implemented in conjunction with the {@link PropertyEditorRegistry} interface.
  *
+ * <p><b>Note:</b> Since TypeConverter implementations are typically based on
+ * {@link java.beans.PropertyEditor PropertyEditors} which aren't thread-safe,
+ * TypeConverters themselves are <em>not</em> to be considered as thread-safe either.
+ *
  * @author Juergen Hoeller
  * @since 2.0
  * @see SimpleTypeConverter